Method of obtaining solutions or quasi solutions of certain metallic oxids.



UNITED STATES PATENT OFFICE.

ZACHARIAH CARTWRIGHT, OF ILFORD, ENGLAND.

METHOD OF OBTAINING SOLUTIONS OR QUASI SOLUTIONS OF CERTAIN METALLICOXIIDS.

Specification of Letters Patent.

Patented Dec. 2'7, 1910.

No Drawing. Original application filed June 29, 1909, Serial No.505,045. Divided and this application filed January 12, 1910. Serial No.537,763.

To all whom it may concern:

Be it known that I, ZAGHARIAH CART- WRIGHT, a subject of the King ofGreat Britain, and resident of 33 Clarendon Gardens, Ilford, Essex,England, have invented a Novel Method of Obtaining Solutions or QuasiSolutions of Certain Metallic Oxids, of which the following is aspecification.

The present application is a division'of the application entitled amethod of obtaining solutions or quasi-solutions ofcertain metallicoxids, No. 505,045, filed by me J nne 29, 1909, to which applicationcross reference is here made, wherein is set forth a novel menstruum fortreating metallic oxids, notably those of iron and other metals of theiron group, for the purpose of obtaining a soluble-form of certain ofthese oxids in a chemically inert medium.

My invention relates to a novel process of treating metallic oxids,notably-those of metals contained in the iron series viz., iron,manganese, chromium which are insoluble in Water and other mediachemically indifferent to the said oxids, for the. purpose of obtainingwhat is virtually a soluble form of certain of these oxids in achemically inert medium. I

My invention rests, therefore, upon the discovery I have made of a novelmenstruum for the insoluble oxids referred to which, enables them to beapplied in the form of permanent suspension or quasi solutions to manypurposes to which they have been hitherto inapplicable. By theapplication of my invention I am furthermore enabled to effect (bytaking advantage of the selective action of the menstruum) theseparation of the oxids from those impurities with which they arecommonly assoclated and moreover, within certain limits (as hereafterexplained) to separate the various oxids from one another.

It is to be understood that although i the following description for thesake of convenience I refer'to the mixture of oxid and the saponaceousmenstruum as a susstituent elements will pass through filter papertogether with the soluble fatty acids that "I include in the term soapresin soap and aqueous solutions of fatty acids with a sufiiciency ofalkali to hold the fatt acids in solution. Too great an excess 0 alkalimust be avoided, otherwise more or less rapid precipitation. of theoxids ensues; A certain proportion of 'unsaponified' fats or glycerinmay be present in the soap-solution without detriment to the process.

In the manufacture of mottled soap,

more rapidlydoes the iron oxid sink to the bottom of the semi-fluidmass. f This still it is well known that if iron oxid be employed to.produce the mottling, the greater the proportion of water present theholds good for high degrees of dilution of the soapy mattercorresponding to or 90 in a decrease in the rapidity of precipitation.

The increase in what as above stated, may, for convenience sake, becalled the suspension of the ox'id,iconsequent on further di-' lution,is very rapid, a maximum being reached between the limits of 1 and 0.5%

concentration. If the soap solution be of 1% concentration,precip'itationof the oxid practically ceases, 2'. e. the oxid willremain suspended in, or distributed throughout the A soap solution,without any perceptible tendency to become deposited under the action ofravity for a practically unlimited perio The above appliesto other oxidsbesides those of iron, for instance those of manganese and chromium.Itis however,

; only the hydrated oxids which may be suspended, using this term in thesense above indicated, the so-called solubility increasing with thedegree of hydration, specific gravity evidently being the determiningfactor.

Since the color of these oxids also depends upon their hydration (thecolor passing through progressively darker shades when an oxid 1sdehydrated by ignition) it will .be seen that by employing a menstruumof a given predetermined strength, certain one or more li hter (andconsequently more brightly co ored) oxids can be separated from theheavier e. darker) ones by vir-' tue of the selective solvent actionexercised upon them by the menstruum. I have, therefore, discovered anovel'menstruum for lI'OIl and other. oxids which for many-purposes maybe regarded practically as water, consisting as it does of an extremelydilute aqpeous solution of the comparatively inert su stance soap,and'bein therefore a very innocuous vehicle or medium for conveying theoxid. It will be evident that by the use of this menstruum these bodiesmay be applied to many purposes to whichthey were hitherto, in theabsence of such a menstruum,

- chromium, I may proceed as follows. I

of 5 to 0.5%.

suspend the finely levigated impure oxid in the prepared menstruum withmechanical stirring. ,The strength of the menstruum may be anythingbetween the limits, say, The mixture obtained as above is allowed tostand, whereupon the impurities, both those such as silica associatedwith the oxid and those in the water, will precipitate. Too much oxidshould, of course, not be introduced into the solution (2'. e.,not somuch as to appreciably afieet the fluidity of the mixture) otherwisesatisfactory separation will not be obtained. I find 7% of oxid to beabout the maximum for good results. As soon as this precipitation hasceased the solution, containing the oxid and a certain amount of themore soluble impurities, is decanted off into another Vessel and a smallquantity of alkali is then added to-it. Both the impurities and the oxidareprecipitated, although the latter goes down more slowly andconsequently the precipitate obtained will form two distinct layers,whereof the lower layer consists of impurities, insoluble oxids, and themore coarsely powderedoxid, while the upper one consists of practicallypure metallic oxid whose precipitation has taken place more slowly. Inorder to obtainthe pure oxid it is only necessary to decant off themenstead of adding the alkali subsequent to the separation of theimpurities, to commence with a menstruum containing a somewhat largeexcess (relatively speakin of alkali.

Such a menstruum may be cal ed a time solution since all the oxids willbe precipitated from it after a space of, say, two hours and inaccordance with the percentage of alkali used. The above operations maybe repeated if desired, successive operations yielding a purer or morefinely divided precipitate of oxid. The above constitutes a ready andinexpensive method of purifying metallic oxids to be employed in themanufacture of paint and the like. I

In order to illustrate what the strengths of the menstruum mean, I willdescribewhat I mean by, say, a 1% menstruum. Dissolve 1 lb. of causticsoda or caustic potash in about 8 lbs. of water, then take 1 lb. ofrosin, grease or oil and warm it until liquid, then pour it slowly intothe alkali solution, stir up until well mixed and allow to stand forabout 7 days, after which boil up and add slowly further water until aquite clear fluid is obtained in 198 lbs. of water; this I call a 1%solution.

My invention'finds its most important applicationin the partialseparation (accord ing to color) of mixed oxids from one another, withthe ultimate object of applying them as pigments in the manufacture ofpaints and the like.

Although for the reasons hereinafter specified, it is not practicable,according to the process the subject of my invention, to absos.

lutely separate any required oxid from those others withwhich it isassociated (and which may difier from it either according to the natureof the-metals concerned or in their respective percentages of combinedwater) so as to obtain a single pure oxid of definite composition,nevertheless this is of small consequence, the object in View beingsimply the assortation of the oxids according to shade so as to obtainsamples of the brightest shades suitable for the manufacture of paints.

The process may be described as an empirical one, the problem being toobtain from any given specimen of mixed oxids, a sample or series ofsamples of mixed oxids of any required shade (the shade being determinedby the varying preponderance of the lighter and darker oxids), while themethod adopted depends upon the fact that from a solution of the mixedoxids precipitation of the different oxids present takes place in theorder of their respective specific gravities.

. in the action, that is to say there is no sharply defined limitdetermining precipitation of one oxid only or, alternately, of that oxidand also the next in order of specific gravity, the reality being thatas a given limit is approached not only does the rapidity ofprecipitation of the heavier oxid increase, but the next in order ofgravity also commences to precipitate until when the limit is actuallyreached both oxids are precipitated with practically equal rapidities.Hence it will be seen that by the. application of this principle, it ispossible to obtain,

from a given specimen of mixed oxids, an infinite number of samplescontaining progressively increasing proportions of an oxid of any g1venspecific gravity. Since the color of these oxids is darker according asthe specific gravity and percentage of combined water is higher, it willbe evident that any shade may be obtained within the range of colorspresented by the oxlds dealt with. In the case of iron and manganese,however, the specific gravities of oxids containing correspondingpercentages of oxygen and of combined water do not permit of completeseparation by the application of this method.

In carrying out the assortation process I proceed as follows. Suppose itis'required to repare a sample of mixed oxids of an orange-yellow shade.Th1s shade Wlll of course correspond with a certain high percentage ofthe lighter oxids, the numerical value of this percentage being howeverof no immediate consequence. The object is to obtaina menstruum of suchstrength as will dissolve the oxid of lightest color and that proportionof the darker oxids, ,the presence of which is necessary to impart theshade required to the mixture of oxids dissolved.

WVhen a fluid of the required shade is ob-.

tained, it is run off, and, if the color is required for the preparationof paint or the like, the whole of the oxids contained in this fluid arethereafter precipitated, washed and dried, and are then ready for themarket. In-carrying out this process I proceed according to a method oftrial and error,

i. e. employing a small test sample of oxid, I commence with a weak'menstruum and gradually increase its strength until one of the correctstrength is obtained. I

It .will be observed that, in the foregoing example, the process isworked by progressive solution. The details of the process are asfollows :I first prepare a menstruum of sufiicient strength to dissolveall the oxids contained in the specimen to be This menstruum (which Iwill reftreated.

fer to the standard solution) may be of a strength, say of 2%, theprecise meaning which this strength implies having been above explained.From this standard solution I then prepare a small quantity ofa solutionof a strength insufiicient to dissolve any of the oxids, and thereafterincrease its strength until it is found to hold such of the oxids insuspension as will 'give the shade required. When a test solution of therequired strength has been obtained, its strength can be easilycalculated from the proportions of water and standard solution employed.A quantity of the menstruum of the required stren th can then beprepared for the purpose 0 obtaining a pigment of the required shadefrom the specimen of commercial oxid submitted; All that is nec essaryis to decant off the solutions of color and to thereafter precipitateitwith an alkali, care being taken that only the requisite quantity ofpreei itant is employed.

Owing to the .act that no two specimens of commercial oxid can ever berelied upon to possess the same uniform composition, and that moreover,no satisfactory method is known of determining such percentagecomposition, it will be found necessary always to proceed in the abovemanner by operating first with a test solution. Furthermore,

since the foregoing remarks apply with equal force to the soap suppliedin commerce (2'. e. the percentage'of fatty acids and alkali obtainablein solution from any given specimen of soap being indefinite) and moreover,'the hardness of the water employed being also a factor which mustbe taken into consideration, I find it necessary to prepare the soapsolution according to the special process above described.

\ If it be desired to prepare a permanent fluid suspension of an oxid,it is only necessary to employ a menstruum of the maxi-,

mum suspension power. By this means the insoluble impurities are at onceprecipitated whereupon the solution of metallic oxid may then bedecanted off and be preserved indefinitely. To obviate the consequencesof such an excess of alkali in the menstruum as would cause gradualprecipitation, advantage may be taken of the factthat certain organlcsubstances, such a sugar, tend to prevent the precipltation of ferricoxid by alkalies.

Claims. v

1. A process for separating certain metallic oxids, consisting inplacing the said oxids in an aqueous solution having not less than 0.5per cent. of a saponaceous material; then increasing the percentageslowly to obtain the'desired color, then precipitating the oxids in thesaid solution by the adlution by the addition of an alkali thereto; 10dition of an alkaln and then decanting the and then decanting the liquidcarefully to liquid. obtain separate layers of liquid varying in Apocess of separating certaliln med color I 5 ta lic oxi s consistin' inlacin t e sai r oxids in an aqueous so utioli haviiig not less[JACHARIAH CARTWRIGHI? than one-half of one per cent. nor more thanWitnesses:

five per cent. of a saponaceous material; EDWARD GEORGE WHITE,

then precipitating the oxids in the said so- Ro'sn ISABEL PAGE.

